HIV prevalence in sub-Saharan Africa (SSA) is highest of any global region, and females in SSA are at highest risk. In Kenya, adult HIV prevalence has declined nationally except in the west (Nyanza). HIV incidence among Kenyan youth aged 15-24 did not change between 2007-12, suggesting that more innovative and effective HIV prevention and treatment is urgently needed. Women ages 15-24 in Kenya are 2-3 times more likely than males to be HIV-infected. Related risks of teen pregnancy contribute to vertical HIV. There is a wide gap between these epidemiologic risks and targeted delivery of efficacious interventions for young women to get testing, prevention or linkage to HIV treatment. Our scientific team including researchers, implementers, and Ministry of Health, is productively engaged in a current gender-specific combination HIV prevention study for youth that the proposed work will leverage. We propose an implementation science framework to address the HIV prevention and treatment continuum that will inform best practices in identifying high-need young women, providing testing options, and primary HIV prevention as well as linkage to HIV care, in SSA. AIM 1: We propose to identify female youth ages 15-24 years at risk for HIV in Nyanza, Kenya who have not had a HIV test within the past six months, utilizing 1) community-based (n?500) and 2) home-based (n?500) 'seek' strategies and compare HIV test uptake and prevalence (yield). Logistic regression analysis will determine which recruitment strategy yields a higher rate of newly diagnosed HIV infection. Enrolled young women (n?1,000) will be offered 1) HIV oral fluid self-testing (OST), 2) staff-aided testing (HTC) and 3) standard provider/facilit-based testing to determine this population's preference for location and modality of HIV testing services based on uptake patterns. Multinomial logistic regression will be used to understand which testing approaches are preferred by female youth. AIM 2: We will pilot and evaluate an adaptive intervention ('SMART' trial) to link HIV-positive female youth (anticipated n=100) to HIV treatment. We will randomize participants to receive text-messages/SMS or standard referral; those who do not link to care will then be re- randomized to receive 1) one-time financial incentive to link to care vs. 2) SMS reminders. We will also use the SMS platform to deliver targeted messages around recommended 6-month HIV re-testing, and risk reduction behaviors, to high-risk HIV negatives to support high-impact prevention. We will re-test a random subset of these HIV-negatives (n=100) to document HIV status at 12 months, and survey them regarding HIV testing and prevention service access between baseline and follow-up. AIM 3: We will conduct an economic evaluation, using both cost-effectiveness and cost-benefit analyses, to determine the relative utility of each of the Aims 1-2 seek, test, link, and prevention interventions. We will share study findings with Government of Kenya to inform design of their planned national electronic HIV SMS system, strengthen national rollout for HIV self-testing, and enhance high-impact HIV prevention and treatment for the most vulnerable young women.